Figure 4

Position-specific enrichment of uncapped 5′-ends surrounding a poly(A) signal-like element. Distribution of normalized reads around the AATAAA and AAAAAA sites in the 3′ UTR of Arabidopsis genes (A and C) and rice genes (B and D) is visualized by MORPH. Loci containing the motif of interest were identified from the 3′ UTR of all annotated genes and the number is shown in parentheses above the heat map. Only loci with a total read number greater than five in the 20-nt region are shown and the number of loci in each heat map is also indicated above the heat map. Motifs were boxed with the first nucleotide set as 1. Loci were clustered based on the distribution of normalized read numbers across the 20-nt region by Ward’s method. Base composition upstream and downstream of the AATAAA sites identified in the motif analysis of Tx4F library in the 3′ UTR of Arabidopsis genes (E).